Whether or not that fits with one's definition of necromancy is neither here nor there (though to say "there is no necromancy involved" is again an entirely personal view)

If you remember you said:

"but still I see no mention of actually raising and reanimating dead corpses.. I merely see possession of the living be they human or animal by a dead spirit..."

The barrow wights are clearly an example of this. They are corpses re-animated by evil spirits (on the impetus of the WK, probably).

You seem to be arguing against the proposition that Tolkien's meaning of the term "The Necromancer" must have included the idea of raising the dead because of the existance of the barrow wights. No such proposition has been suggested.